Add support for :rmdir

The `:rmdir` command removes the current directory (`-f` is required if
the directory is not empty).

This is not supported on the notmuch backend.

An issue with the maildir backend is that some sync programs (e.g.
offlineimap) may recover the directory after it is deleted.  They need
to specifically be configured to accept deletions, or special commands
need to be executed (e.g. `offlineimap --delete-folder`) to properly
delete folders.

A danger of using this on the IMAP backend is that it is possible for a
new message to be added to the directory and for aerc to not show it
immediately (due to a slow connection) - using `:rmdir` at this moment
(with `-f` if the directory already contains messages) would delete the
directory and the new message that just arrived (and all other
contents).  This is documented in aerc(1) so that users are aware of
possible risks.

8 files changed, 161 insertions, 0 deletions

diff --git a/commands/account/rmdir.go b/commands/account/rmdir.go
new file mode 100644
index 0000000..ed24ca5
--- /dev/null
+++ b/commands/account/rmdir.go
@@ -0,0 +1,96 @@
+package account
+
+import (
+	"errors"
+	"time"
+
+	"git.sr.ht/~sircmpwn/getopt"
+
+	"git.sr.ht/~sircmpwn/aerc/widgets"
+	"git.sr.ht/~sircmpwn/aerc/worker/types"
+)
+
+type RemoveDir struct{}
+
+func init() {
+	register(RemoveDir{})
+}
+
+func (RemoveDir) Aliases() []string {
+	return []string{"rmdir"}
+}
+
+func (RemoveDir) Complete(aerc *widgets.Aerc, args []string) []string {
+	return nil
+}
+
+func (RemoveDir) Execute(aerc *widgets.Aerc, args []string) error {
+	acct := aerc.SelectedAccount()
+	if acct == nil {
+		return errors.New("No account selected")
+	}
+
+	force := false
+
+	opts, optind, err := getopt.Getopts(args, "f")
+	if err != nil {
+		return err
+	}
+	for _, opt := range opts {
+		switch opt.Option {
+		case 'f':
+			force = true
+		}
+	}
+
+	if len(args) != optind {
+		return errors.New("Usage: rmdir [-f]")
+	}
+
+	// Check for any messages in the directory.
+	if !acct.Messages().Empty() && !force {
+		return errors.New("Refusing to remove non-empty directory; use -f")
+	}
+
+	curDir := acct.SelectedDirectory()
+	var newDir string
+	dirFound := false
+
+	if oldDir, ok := history[acct.Name()]; ok {
+		if oldDir != curDir {
+			newDir = oldDir
+			dirFound = true
+		}
+	}
+
+	if !dirFound {
+		for _, dir := range acct.Directories().List() {
+			if dir != curDir {
+				newDir = dir
+				dirFound = true
+				break
+			}
+		}
+	}
+
+	if !dirFound {
+		return errors.New("No directory to move to afterwards!")
+	}
+
+	acct.Directories().Select(newDir)
+
+	acct.Worker().PostAction(&types.RemoveDirectory{
+		Directory: curDir,
+	}, func(msg types.WorkerMessage) {
+		switch msg := msg.(type) {
+		case *types.Done:
+			aerc.PushStatus("Directory removed.", 10*time.Second)
+		case *types.Error:
+			aerc.PushError(" " + msg.Error.Error())
+		case *types.Unsupported:
+			aerc.PushError(":rmdir is not supported by the backend.")
+		}
+	})
+
+	return nil
+}
diff --git a/doc/aerc.1.scd b/doc/aerc.1.scd
index 89189d5..c2f813a 100644
--- a/doc/aerc.1.scd
+++ b/doc/aerc.1.scd
@@ -214,6 +214,28 @@ message list, the message in the message viewer, etc).
 *mkdir* <name>
 	Creates a new folder for this account and changes to that folder.
 
+	This is not supported on the 'notmuch' backend.
+
+*rmdir* [-f]
+	Removes the current folder.
+
+	By default, it will fail if the directory is non-empty (see *-f*).
+
+	*-f*
+		Remove the directory even if it contains messages.
+
+	This is not supported on the 'notmuch' backend.
+
+	Some programs that sync maildirs may recover deleted directories (e.g.
+	offlineimap).  These can either be specially configured to properly
+	handle directory deletion, or special commands need to be run to delete
+	directories (e.g. 'offlineimap --delete-folder').
+
+	It is possible, with a slow connection and the 'imap' backend, that new
+	messages arrive in the directory before they show up - using 'rmdir' at
+	this moment would delete the directory and such new messages before the
+	user sees them.
+
 *next* <n>[%], *prev* <n>[%]
 	Selects the next (or previous) message in the message list. If specified as
 	a percentage, the percentage is applied to the number of messages shown on
diff --git a/widgets/account.go b/widgets/account.go
index bb29ce0..f279513 100644
--- a/widgets/account.go
+++ b/widgets/account.go
@@ -237,6 +237,8 @@ func (acct *AccountView) onMessage(msg types.WorkerMessage) {
 			}
 		case *types.CreateDirectory:
 			acct.dirlist.UpdateList(nil)
+		case *types.RemoveDirectory:
+			acct.dirlist.UpdateList(nil)
 		}
 	case *types.DirectoryInfo:
 		if store, ok := acct.dirlist.MsgStore(msg.Info.Name); ok {
diff --git a/worker/imap/remove.go b/worker/imap/remove.go
new file mode 100644
index 0000000..47b1f43
--- /dev/null
+++ b/worker/imap/remove.go
@@ -0,0 +1,19 @@
+package imap
+
+import (
+	"git.sr.ht/~sircmpwn/aerc/worker/types"
+)
+
+func (imapw *IMAPWorker) handleRemoveDirectory(msg *types.RemoveDirectory) {
+	if err := imapw.client.Delete(msg.Directory); err != nil {
+		if msg.Quiet {
+			return
+		}
+		imapw.worker.PostMessage(&types.Error{
+			Message: types.RespondTo(msg),
+			Error:   err,
+		}, nil)
+	} else {
+		imapw.worker.PostMessage(&types.Done{types.RespondTo(msg)}, nil)
+	}
+}
diff --git a/worker/imap/worker.go b/worker/imap/worker.go
index 0be51d7..c016af6 100644
--- a/worker/imap/worker.go
+++ b/worker/imap/worker.go
@@ -165,6 +165,8 @@ func (w *IMAPWorker) handleMessage(msg types.WorkerMessage) error {
 		w.handleFetchDirectoryContents(msg)
 	case *types.CreateDirectory:
 		w.handleCreateDirectory(msg)
+	case *types.RemoveDirectory:
+		w.handleRemoveDirectory(msg)
 	case *types.FetchMessageHeaders:
 		w.handleFetchMessageHeaders(msg)
 	case *types.FetchMessageBodyPart:
diff --git a/worker/maildir/worker.go b/worker/maildir/worker.go
index d1ff3c2..4a7ae51 100644
--- a/worker/maildir/worker.go
+++ b/worker/maildir/worker.go
@@ -186,6 +186,8 @@ func (w *Worker) handleMessage(msg types.WorkerMessage) error {
 		return w.handleFetchDirectoryContents(msg)
 	case *types.CreateDirectory:
 		return w.handleCreateDirectory(msg)
+	case *types.RemoveDirectory:
+		return w.handleRemoveDirectory(msg)
 	case *types.FetchMessageHeaders:
 		return w.handleFetchMessageHeaders(msg)
 	case *types.FetchMessageBodyPart:
@@ -362,6 +364,16 @@ func (w *Worker) handleCreateDirectory(msg *types.CreateDirectory) error {
 	return nil
 }
 
+func (w *Worker) handleRemoveDirectory(msg *types.RemoveDirectory) error {
+	dir := w.c.Dir(msg.Directory)
+	if err := os.RemoveAll(string(dir)); err != nil {
+		w.worker.Logger.Printf("could not remove directory %s: %v",
+			msg.Directory, err)
+		return err
+	}
+	return nil
+}
+
 func (w *Worker) handleFetchMessageHeaders(
 	msg *types.FetchMessageHeaders) error {
 	for _, uid := range msg.Uids {
diff --git a/worker/notmuch/worker.go b/worker/notmuch/worker.go
index f14b7ff..66d1cd2 100644
--- a/worker/notmuch/worker.go
+++ b/worker/notmuch/worker.go
@@ -131,6 +131,8 @@ func (w *worker) handleMessage(msg types.WorkerMessage) error {
 		// 	return w.handleAppendMessage(msg)
 		// case *types.CreateDirectory:
 		// 	return w.handleCreateDirectory(msg)
+		// case *types.RemoveDirectory:
+		//  return w.handleRemoveDirectory(msg)
 	}
 	return errUnsupported
 }
diff --git a/worker/types/messages.go b/worker/types/messages.go
index 374db81..ab0e545 100644
--- a/worker/types/messages.go
+++ b/worker/types/messages.go
@@ -92,6 +92,12 @@ type CreateDirectory struct {
 	Quiet     bool
 }
 
+type RemoveDirectory struct {
+	Message
+	Directory string
+	Quiet     bool
+}
+
 type FetchMessageHeaders struct {
 	Message
 	Uids []uint32